HOUSTON — The Red Sox placed reliever Matt Thornton on the 15-day disabled list Wednesday with a left oblique strain, recalling Pedro Beato from Triple-A Pawtucket to take his place on the 25-man roster.

Thornton originally hurt his his oblique during an appearance Sunday afternoon against Arizona on his fourth pitch of his outing.

“Hopefully it’s a minor thing and I’m back in 15 days,” Thornton said. “From talking to guys who have had it, I’ve never had this before in my entire career, everyone said they’ve tried to come back too quick. I didn’t want that. I want to be fresh and be ready to go as soon as possible. … It’s gotten better every day. I’ve been here doing as much as I can, getting treatment as much as possible. It feels better, but at the same time you can’t jeopardize the other arms in the bullpen by being a man short.”

Thornton has appeared in 10 games for the Red Sox since coming over in a trade from the White Sox, allowing two runs on 12 hits over 8 1/3 innings.

“When you get into the oblique injury, even though he feels improved over the time on Sunday when he first suffered the injury, this is something we feel we don’t’ want to rush with the potential of any kind of setback,” Red Sox manager John Farrell said prior to his team’s game against the Astros Wednesday. “The fact was that we also needed an arm in here after last night’s bullpen use. And we felt the projected return to game activity is going to be every bit of two weeks, even with the improvement he showed the last couple of days.”

Mike Napoli sat out the series finale against the Astros, with Mike Carp getting the start at first base. Napoli has hit just .200 with 20 strikeouts in 50 at-bats since learning his hip condition hadn’t worsened after a July 20 MRI.

“Today was a day to get him off his feet,” Farrell said. “It was pretty much scheduled before the extra work was accomplished today. He needed some focused work to try and reproduce that more direct bat path through the point of contact. He’s been grinding of late, but felt the extra work was needed and a day off his feet.”

The manager added, “I think right now, he’s grinding and as a result I think the swing has gotten a little bit longer at times and that’s where you see him having to commit earlier to above average velocity, and does that make him susceptible to a bigger strike zone, possibly. These are things that are being addressed daily and certainly with the early work today.”

Farrell wouldn’t confirm that the team was contemplating moving Napoli down in the lineup, only saying. He also noted that while the first baseman’s hips weren’t an issue, the player was dealing with some other aches and pains.

“He’s got some things going on ‘ not the hip, the hip’s not part of it ‘ like anybody else there’s ailments that guys are dealing with, not to the point of it being the reason for some things, or a stretch of performance,” Farrell said. “He’s managing things just like everybody else.”

MORALES RETURNS TO MOUND

After leaving his rehab assignment for a short while due to personal issues, Franklin Morales was back with Double-A Portland Wednesday with the intention of pitching an inning. Farrell said the lefty is close to returning to the big league club.